LTC3203_15 Datasheet, PDF (14/16 Pages) Linear Technology – 500mA Output Current Low Noise Dual Mode Step-Up Charge Pumps

LTC3203/LTC3203-1
LTC3203B/LTC3203B-1
APPLICATIO S I FOR ATIO
Thermal Management
For higher input voltages and maximum output current,
there can be substantial power dissipation in the LTC3203/
LTC3203-1/LTC3203B/LTC3203B-1. If the junction tem-
perature increases above approximately 150°C, the ther-
mal shutdown circuitry will automatically deactivate the
output. To reduce the maximum junction temperature, a
good thermal connection to the PC board is recommended.
Connecting GND (Pin 9) and the exposed pad (Pin 11) of
the DFN package to a ground plane under the device on two
layers of the PC board can reduce the thermal resistance
of the package and PC board considerably.
Layout Considerations
Due to the high switching frequency and high transient
currents produced by the LTC3203/LTC3203-1/
LTC3203B/LTC3203B-1, careful board layout is neces-
sary for optimum performance. A true ground plane and
short connections to all the external capacitors will
improve performance and ensure proper regulation
under all conditions.
The flying capacitor pins C1⁺, C2⁺, C1^– and C2^– will have
very high edge rate waveforms. The large dV/dt on these
pins can couple energy capacitively to adjacent printed
circuit board runs. Magnetic fields can also be generated
if the flying capacitors are not close to the part (i.e. the loop
area is large). To decouple capacitive energy transfer, a
Faraday shield may be used. This is a grounded PC trace
between the sensitive node and the LTC3203/LTC3203-1/
LTC3203B/LTC3203B-1 pins. For a high quality AC ground
it should be returned to a solid ground plane that extends
all the way to the LTC3203/LTC3203-1/LTC3203B/
LTC3203B-1. To prevent degraded performance, the FB
trace should be kept away or be shielded from the flying
capacitor traces.
GROUND PLANE
C_OUT
C1
C2
1
10
2
9
3
11
8
4
7
5
6
C_IN
LTC3203/LTC3203B COMPONENTS NOT USED
IN LTC3203-1 OR LTC3203B-1
3206 F07
Figure 6. Recommended Layouts
32031fa
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